Paint



Patented Oct. 2, 1945 PAINT Alfred Donty, Elkins Park, and Frank B.Freese, Lansdale, Pa., assignors to American Chemical Paint Oompany,Ambler, Pa., a corporation oi Delaware No Drawing.

Application February 27, 1941,

Serial No. 380,770

2 Claims.

This inventiom relates to siccative finishing compositions such aspaint, varnish, lacquer, etc., and in the following disclosure andclaims the term paint"will be employed as a generic term forcompositions of this character.

The primary object of the invention is to provide a paint which willyield exceptionally adherent and strongly corrosion resistant finishes,especially on metal surfaces. A further object is to provide a primerwhich is particularly well adapted to serve as a foundation or base uponwhich to apply subsequent finishing coatings.

A still further object of the invention is to provide a metal primerwhich can be directly applied to surfaces which are contaminated withsmall amounts of rust, corrosion products, or rust stimulative materialslike soluble chlorides, etc., without the necessity for preliminarilycleaning or otherwise treating the surface to be painted. Morespecifically our invention renders unnecessary certain preliminarytreatments heretofore customary in the art, such, for example, ascleaning with phosphoric acid olutions, or the application to metalsurfaces of phosphate base coatings.

Other objects of the invention include the provision of a paint whichwill greatly lessen the cost of a complete finishing Job as well as onewhich will materially increase the life of the finish.

Still other objects and advantages will appear to those skilled in thisart as the description proceeds.

In its broadest aspect our invention consists in the provision of apaint or similar siccative finishing composition which includes asubstantially water-insoluble or water immiscible film forming vehicle(either pigmented or unpigmented), which vehicle is emulsified as a dispersed internal phase in a continuous, aqueous acid external phase. Theacid used in the external aqueous phase should react with someconstituent of the particular surface to which the composition is to beapplied to produce or leave behind only such residual end products asare stable, substantially water-insoluble and inert toward the depositedcoating of film forming vehicle and for this reason we prefer phosphoricacid, especially where the paint is to be applied to metal surfacesbecause phosphoric acid is metal etching and non-corrosion stimulative.-

The emulsiflcation of the film-forming vehicle in the external acidaqueous phase may be accomplished by any means known to those skilled inthe art, although we have found that very superior results are obtainedwhen the emulsification is accomplished by means which includes acationic surface active agent as will be more fully describedhereinafter. However, entirely successful compositions have beenprepared by means of other emulsifying agents such. for example, ashydrophile colloids, as well as combinations of surface active agentsand hydrophile colloids.

Where our composition is to be employed in the finishing of metalsurfaces, the aqueous external phase may also include, if desired,suitable regulators of the rapidity of reaction of the acid with thesurface of the metal to which the paint is to be applied. Agents of thiskind which may be used are, among others, inhibitors of acid attack onmetal and/or bufier salts of metals not otherwise harmful either to themetal surface or to the finish which, after the evaporation of the waterand the reaction of the acid with the metal surface, leave behindsubstantially water-insoluble residues only. Among such buffer salts maybe mentioned the phosphates of zinc, magnesium, iron, calcium,manganese, cadmium, etc.

The internal dispersed phase may include, for example, drying oils,natural resins, synthetic resins, varnishes, cellulose others, etc.. inaddition to pigments, fillers, solvents, diluents, etc. It must be socompounded that it remains sufficiently fluid to enable its discretedrops to flow on the surface and coalesce to a substantially continuousfilm which will remain in this condi tion until the water of theeitternal phase has evaporated and the reaction of the aqueous acidsolution with the surface of the metal has substantially ceased. To thisend, it is desirable, especially when the film-forming vehicle is highin resin solids, to have present in the dispersed phase a solvent orsolvent system which evaporates more slowly than water and which, Justbefore the complete evaporation of the water, still remains insufficient quantity to allow some "leveling" of the paint on thesurface, so that the paint will not show "spatter marks if sprayed, norbrush marks if ibrushed. Moreover, the presence of such a solvent systemyields an additional advantage in that it ensures the healing" of anyholes left in the film by gas bubbles from the reaction of the acidaqueous solution with the surface of the metal, so that, as the paintfilm dries, any such holes due to the release of gas bubbles will besubstantially eliminated in the final finish.

We have found that any oils, resins, or other vehicle solids may be usedas the dispersed phase except such as are caused to gel or set" or areotherwise adversely affected by the acid environment in which thedroplets of paint are suspended. Similarly, carbonates or other pigmentsor fillers which are easily affected by acids are not to be used, butotherwise no limitations in pigmentation have been encountered.

We have also found it desirable to add to our composition small amountsof an organic liquid blending agent somewhat soluble in the water of theaqueous phase and somewhat soluble also in the non-aqueous phase orfilm-forming phase and having the property of reducing the surfacetension of both phases. Among agents of this character which we havefound to be useful with our invention are the aliphatic alcohols 01' notmore than eight carbon atoms and glycol others such as "cellosolve and"butyl cellosolve. These liquids, of which normal butyl alcohol, amylalcohol (fusel oil) and secondary octyl alcohol are examples, have twodesirable effects in our composition: first, they promote the dispersionof the substantially water-insoluble paint vehicle as the internal ordispersed phase in the aqueous liquid portion, so that the latter formsthe continuous or external phase. This is sometimes diilicult to achievein the absence of such blending agent, particularly when a relativelysmall amount of the aqueous phase is present as compared with thewater-insoluble or oily" phase. This latter condition is encountered,for example, whenever it is desired to increase the viscosity or paintvehicle solids" of our composition, as. for instance, when it is to beapplied by brushing instead of by spraying, or when increased filmthickness of the final coating is desired. Second. such "blending agentspromote leveling of the film of deposited paint.

In order to still further vary the stability or viscosity of theemulsions which constitute our compositions, it may further be desirableto incorporate therein a hydrophile colloid. Among such emulsionprotective and thickening agents may be mentioned colloids such as glue,agar, solid colloidal agents like colloidal clay or bentonite; watersoluble gums including cellulose others such as methyl cellulose, etc.These agents generally have a beneflcialeilect on the smoothness andtexture of the deposited film.

Where metals are to be painted we have referred above to the use of thenon-corrosion stlmulative phosphoric acid which is capable of etchingthe metal and of forming therewith or with any rust or surfacecontaminants which may be present thereon, relatively stable,substantially water-insoluble salts or basic salts of such a nature thattheir presence either on the metal itself or in the paint film does notstimulate corrosion by atmospheric agencies. In addition, the residualend reaction products of such acid is stable, substantiallywater-insoluble and inert toward the deposited coating of film-formingvehicle, as stated above.

The surface-active agents referred to above are in general organicsubstances which yield in aqueous solution ions that are stronglyadsorbed on the surfaces of oily" materials with which the aqueoussolution comes in contact. when such oily substances are broken up intofine droplets by mechanical or other means within such aqueoussolutions, the droplets are prevented by their surface layers ofadsorbed ions from coalescing; thus a more or less stable emulsion ofthe oil in the water results. The "oily" drops of our improvedcomposition are the film-forming or paint vehicle, 1. e., the oils,resins, pigments, fillers and solvents originally composing the layer tobe deposited on the surface to which the composition is to be applied.

Our experience has shown that for use in our compositions agentsyielding positively charged surface active ions, so-called cationicsurfaceactive agents are strongly indicated. Among thecationic-surface-active agents which we have found useful are a numberof compounds defi nitely characterized chemically, and certain othersknown to use only by more general propcities and names. In general, thecompounds found useful include amines and quaternary ammonium saltshaving at least one radical containing twelve or more carbon atoms;amidoamines or quaternary ammo-ammonium salts having radicals containingtwelve or more carbon atoms; and ester-amines containing similarradicals.

Specifically, fatty acids esters of triethanoiamine, fatty acid amidesof hydroxyethyl ethylene diamine, lauryl dimethylamine, etc. were founduseful. In addition certain commercial materials, chemicallycharacterized only as "amines." or "imines" were found satisfactory. Oneof these is known as "Amine E0," others as Acco Emulsifler #2 and #3.

In general, we have found operative a sumclent number of so-calledcationic surface-active agents so that we believe that we are .iustifiedin concluding that the entire class of such materials is operative inthe compositions of our invention.

An example of a quick-drying, pigmented composition according to ourinvention suitable for application to structural steel surfaces as aprimer may be compounded as follows:

A varnish is prepared according to the following formula:

Formula N0. 1-Vomish Pounds Alkyd resin modified with oils and phen0152.5 Modified phenolic resin, melting range 215-232 1" 17.5 Toluol 25.0Secondary octyl alcohol 5.0

Total 100.0

Using this varninsh, a paste is prepared by grinding together, forinstance, in a stone paint mill, the following:

Formula No. 2-Paste Pounds Varnish of Formula No. l 27.27 High flashsolvent naphtha 27.27 Red iron oxide 13.64 Barytes 18.64 Asbestlne 18.18

Total 100.00

The composition ready for use is then prepared as follows:

Formula No. 3-Finished material Pounds Paste, Formula No. 2 40.00Varnish, Formula No. 1 10.00 Phosphoric acid, 75% 1.72 Mono-oleyi esterof triethanolamine--- 2.78 Normal butanol 10.08 Water 35.42

Total 100.00

ii necessary. although water slightlyacidifled with phosphoric acid ispreferable. as impurities, especially lime salts, in the water may havea deleterious eil'ect on the emulsion unless the water is ilrst slightlyacidified.

. 'In the above composition, as in other compositions otour invention,other cationic surfaceactive agents may be used in place oi themonooieyl ester of triethanolamlne specified above. Successfulpreparations have been made with all the emulsifying agents enumeratedabove and others. As all emulsifying agents of this type are not ofequal power, it may be desirable somewhat to vary the amounts used inthe composition. In general it may be stated that it is preferable touse no more emulsifying agent than is necessary to produce an"oil-in-water" type emulsion of adequate stability.

ii, in attempting to prepare our compositions the emulsion formsinitially as, or reverts on standing, to a water-in-oil type in whichthe "paint-like" portion of our preparation constitutes the externalphase and the aqueous portion the internal or dispersed phase, thepreparation is not satisfactory and must be discarded or retreated sbthat the aqueous phase is the external or continuous and the oily" partthe internal or dispersed phase. Many experiments have shown that ourcompositions, when properly prepared and applied, are highly superior tosuperflcially similar materials not made in accordance with ourinvention.

What we may term the acid emulsion primer" of this invention asexemplified by the foregoing examples, dries to a firm tough coatovernight, and under accelerated tests in the salt spray and highhumidity cabinets as well as under outdoor exposure tests, it has provenitself to be much more resistant to corrosive influences than is anyother primer with which we are familiar. In addition, multi-coatfinishing systems embodying one of our compositions as a primary coat,have exhibited vastly improved results over similar systems embodyingconventional primers, even when these are of so-calied"corrosion-resistant" pes.

The example of our composition given in Formula No. 3 is merelyillustrative of a pigmented, air-drying material made in accordance withthis invention, and embodying a synthetic resin vehicle. As statedabove, various natural and artificial oils and resins may be used inplace of synthetic resins such as are embodied in Formula No. 3. As anexample of a composition embodying a natural drying oil only, we maycite the following:

Formula No. 4

Pounds China-wood oil 20.90 Gum turpentine 10.00 Red iron oxide 5.45Barytes 5.45 Asbestine 7.27 Amine E 2.78 Butyl alcohol 10.08 75%phosphoric acid 1.72 Distilled water 35.45

Total 100.00

This is a commercial high molecular weight amine cationic surface activeagent made by the Carbide and Carbon Chemicals Corporation.

oil; then mixingtogether the paste, the rest of the oil. and the AmineE0, and emulsifying the mixture in the water in which the acid has beendissolved.

As previously indicated, the pigment composition of Formula No. 3 andFormula No. 4 may be altered as desired to change the color or otherproperties of the deposited film as will be apparent to the paintchemist, provided only that the pigment be stable in the presence of theacid solution. A similar preparation may be made by substituting in thematerial of Formula No. 4 an equal weight of boiled linseed oil for theChinawood oil of the formula.

The drying properties of our preparations are, of course. affected bythe composition of the vehicle with respect to oils, resins, etc. Forinstance, the composition of Formula No. 4 dries fairly hard overnightat room temperature, whereas a similar composition containing boiledlinseed oil requires several days to dry. However, in general, whateverthe siccative coating agent in our compositions, the coatings producedfrom our acid emulsions dry much more rapidly than non-acid emulsions ofidentical "non-volatile solids" content.

It has been found, however, that maximum drying speed and adhesion offilms produced with our coating compositions is often obtained at acidcontents higher than the minimum necessary to produce a stableoil-in-water type emulsion with cationic surface active agents. Thiseffect 01' free acidity on the drying time of a coating compositionsimilar to that of Formula No. 3 will now be illustrated:

Two compositions were prepared having the following formulas:

Formula No. 5

Both the above compositions were compounded in the same way as wasFormula No. 3 above.

It will be seen that Formulas No. 5 and No. 6 are identical except forthe fact that Formula. No, 6 contains more phosphoric acid andcorrespondingly less water than Formula No. 5. The amount oi phosphoricacid in No. 5 is only willcient to combine with, neutralize, and bringinto solution in the water, the Amine E0; while the amount of phosphoricacid in No. 6 is suillcient to have in the aqueous phase a considerableexcess of free acid.

When these two preparations were sprayed onto clean steel and galvanizediron panels, the coats produced with No. 6 were dry and tough at thetemperature of the room inside of 16 hours.

The coats produced with No. 5 were still tacky" after 116 hours.

The above effect of free acidity in our compositions has been noted fornumerous formulations and is very striking. It has been found, ingeneral, that even traces of free acidity yielding a pH of 4.5 or belowin the aqueous phase are effective in producing satisfactoryacid-emulsion paints, according to our invention. However, a somewhathigher free acidity such as approximately 0.1 normal is useful inreducing the drying time of the preparations. No sharp upper limits ofacidity have been formed for the allowable acidity of our preparations.Too high an acidity may give rise to an increased susceptibility of thecoatings produced to failure in atmospheres of high humidity, but theseriouness of this effect varies with the metal to which the coating isapplied, the nature of the vehicle, degree of pigmentation, etc. Weprefer compositions having a free acidity corresponding to an aqueousphase 0.1 to 1.0 normal in free acidity as determined, for example, bytitration of a portion of the aqueous phase with standard caustic sodasolution to an end-point pH of about 4.5.

As stated above, the action of the acid on the metal may be regulated orcontrolled by adding to the composition various regulating agents, amongwhich may be included buffer salts, inhibitors, etc., as long as theseleave no soluble rust-stimulative, or otherwise harmful, residues. Thebuffer salts are preferably salts of nonrust-stimulative acids, as, forexample, phosphoric, arsenic, and oxalic acids.

Examples of compositions suitable for quickdrying, as, for instance, bybaking in an oven at 350' i for 30 minutes are given below. Thecompositions of Formulas Nos. ll, 12 and 13 contain, as regulators oracid action, respectively, sine phosphate, manganese phosphate, andarsenious oxide.

Formula. No. 7Zinc Phosphate solution Pounds Zinc oxide 1.500 Phosphoricacid, 75% 6.720 Water 4.115

Total 12.335

The zinc oxide is suspended in the water, the phosphoric acid graduallyrun in, and the whole stirred until all the zinc oxide is dissolved.

Formula No. 8-Manoanese phosphate sodlution 1 Pounds Manganous carbonate1.750 Phosphoric acid, 75% 5.050 Water 1 5.460

Loss of carbon dioxide 0.67

Total 11.500

This is made like No. 7, except that manganous carbonate is used insteadof zinc oxide.

Formula No. 9Low an alkyd resin paste assasoo The paste was made inconventional fashion.

Formula number 10 11 I2 13 Ingredient pounds pounds pounds pounds PasteFormula No. 0 40. 00 low-oil modified alkyd resin, w m m m 40 Af l%soiids in xylol 11.65 ll. 65 11.05 ll. 65 2. 78 2. 78 2. 78 Phosphoricacid. 757 1.12 1.72 1.72 i: Zinc hosphate solution (Fori m a No. 7) 1.35 Manganese phos hate solutlon (Formula 0. 8) l. 72 Arsonious oxide 038 Normal butanol 10. 08 10.08 in. 08 10.! WBW 33. 71 31. 92 32. 06 33.M

100. O0 100. (X) [00. (I) 100. (I)

All of these preparations are prepared by emulsiiying the mixture oi thepaste and alkyd resin in an admixture of the rest of the ingredients asdescribed for Formula No. 3.

The above compositions Nos, 10, 11, 12 and 13 were compared by sprayingthem onto cold rolled steel panels, allowing the coatings to drythoroughly and exposing them in salt spray cabinet maintained at 05 1''.for a period of 240 hours. In addition, a further conventional paint wasprepared by mixing together Paste No. 9 and the same low-oil alkyd resinin the same proportions as used in the above formulas. but substitutingfor all of the other ingredients an equal total weight of toluene as athinner. This material, then, contained exactly the same pigment andnon-volatile paint vehicle as the emulsions of Formulas Nos. 10 to 13,and in the same amounts. It constituted (and will be referred to as) a"conventional" paint. This paint was applied to, dried, and tested onsimilar metal panels simultaneously with the "acid emulsion paints" ofFormulas Nos. 10 to 13, inclusive.

After 240 hours of exposure in the salt spray, the results were asfollows:

Conventional paint 95% failure Acid emulsion paints Little or no failureLittle purpose would be served by multiplying the number of formulasfound to be suitable for the compositions of our invention. Suillce itto say that wide variations, obvious to the paint chemist, arepermissible in the compositions according to our invention. Thepaint-like portion of our preparation, constituting the dispersed phase,may be formulated with wide variations with respect to the relativeproportions of vehicle solids, solvents, thinners, pigments and fillers,and these variations may be expected to produce results in the depositedpaint film similar to those well understood by the paint chemist in thecase of conventional paints. For example:

(a) Compositions suitable for baking or accelerated drying, as well asfor air drying, are easily prepared.

(12) Compositions giving clear varnish or lacquer films have beenprepared with success equal to that obtained with pigmentedcompositions.

(c) Pigmented compositions giving films of various colors are easilymade.

(at) Compositions suitable for brushing as well as spraying, havelikewise been readily formulated. As stated previously. omission of someof the water is often all that is required to make a material ofbrushing instead of spraying consistency. Methyl cellulose and otherthickening materials have likewise been added to the aqueous phase toimprove "body" and brush-ability.

(e) Compositions embodying cooked varnishes and lacquers instead of oilsor "solution varnishes" are readily made.

In general, with due regard only to the requirement that the acidaqueous phase does not deleteriously react with the vehicle resin orpigment, the formulation of our improved composition is almost asflexible and unlimited as the formulation of a conventional paint. Thepaint chemist will readily comprehend the limitations inherent in suchcompositions.

As examples of the widerange of vehicle solids which it has been foundpossible to incorporate into our compositions, we may mention, among theoils, linseed oil, tung oil, soya bean oil, oiticica oil, castor oil,dehydrated castor oil, etc. Nondrying oils have been incorporated forspecial purposes; among the resins we have used alkyd resins of variousdegrees of oil modification, pure phenolic resins both heat hardeningand nonheat-hardening, modified phenolic resins, vinyl polymers,hydrocarbon polymers such as coumarone and indene resins, ester gum,rosin, natural resins, such as copal, congo, kauri, etc. The urea resinsas well as the melamine resins are known to be extremely sensitive toacids, even to acidic pigments. Since they are immediately set" by acidsthe paint chemist would be immediately aware that they should not beused in our compositions.

Ester and ethers of cellulose such as nitrocellulose, cellulose acetate,ethyl cellulose, cellulose aceto-butyrate, etc. are also useful in ourimproved compositions.

Among the pigments are fillers we have found useful are fibrous talc orasbestine, silica, barytes, blanc flxe, titanium dioxide, titanatedgypsum and titanated barytes, carbon black, lampblaclr, red iron oxide,black iron oxide, chrome green oxide, smalt, etc. whiting or othercarbonates are inapplicable because of their well known reactivit withacids. Red lead may be used if the emulsions are freshly made Justbefore use. On

long standing red lead reacts deleteriously with acidity of 1.0 normal.

the acid in our compositions.

Ordinary driers and plasticizers may be present in our composition, and,in general, perform their usual functions.

Our invention has been found particularly useful on metals such as iron,steel, zinc and alloys thereof, although it has also been found usefulon cadmium, lead, copper and aluminum. In addition, our compositionshave yielded excellent results on concrete or cement surfaces and whenpainting such surfaces the preferable acids are, of course, those whichare capable of forming with the lime of the cement substantiallywaterinsoluble, inert and stable salts.

We claim:

1. A siccative paint including organic filmforming material emulsifiedas a dispersed phase in a continuous aqueous phase including phosphoricacid, together with a cation-active emulsifying agent; an organic liquidblending agent from the class consisting of aliphatic alcohols of notmore than eight carbon atoms and glycol ethers; a solvent in thedispersed phase which evaporates more slowly than water; and a pigmentsubstantially unaflectcd by the phosphoric acid; the concentration offree acidity in the aqueous phase being suflicient to impart to thatphase a pH of 4.5 but not more than enough to yield a free acidity of1.0 normal.

2. A siccative paint for use on metals including organic film-formingmaterial emulsified as a dispersed phase in a continuous aqueous phaseincluding phosphoric acid and a buffer salt from the class consisting ofthe phosphates of iron, zinc, manganese, calcium, cadmium and magneslum,together with a cation-active emulsifying agent; an organic liquidblending agent from the class consisting of aliphatic alcohols of notmore than eight carbon atoms and glycol ether-s; a solvent in thedispersed phase which evaporates more slowly than water; and a pigmentsubstantially unaffected by the phosphoric acid; the concentration offree acidity in the aqueous phasebeingsuilicienttoimparttothatphaseapfloi' 4.5 but not more than enoughto yield a free GER'l'IFICliTE or comc'rzos.

Patent No. 2,385,800.

October 2, 19 6.

ALFRED DUUTY, ET AL- It is herebycertified that error appears in theprinted specification of the above numbered patent requiring correctionas follows: Page 2,

column, line 75, for use" read --us--; and

page 5, first column, line 35, for "are" read "and";

read --aci.d-;

first second column, line 9, for"aci.ds"

and

second column, line a, beginning with "and when" strike out all to andincluding the word "salts" in line 12; and that the said Letters Patentshould be read with this correction therein that the some may conform tothe record of the case in the Patent Office.

(Seal) i. o. 191L6- Leslie Frazer First Assistant domissioner ofPatents.

(e) Compositions embodying cooked varnishes and lacquers instead of oilsor "solution varnishes" are readily made.

In general, with due regard only to the requirement that the acidaqueous phase does not deleteriously react with the vehicle resin orpigment, the formulation of our improved composition is almost asflexible and unlimited as the formulation of a conventional paint. Thepaint chemist will readily comprehend the limitations inherent in suchcompositions.

As examples of the widerange of vehicle solids which it has been foundpossible to incorporate into our compositions, we may mention, among theoils, linseed oil, tung oil, soya bean oil, oiticica oil, castor oil,dehydrated castor oil, etc. Nondrying oils have been incorporated forspecial purposes; among the resins we have used alkyd resins of variousdegrees of oil modification, pure phenolic resins both heat hardeningand nonheat-hardening, modified phenolic resins, vinyl polymers,hydrocarbon polymers such as coumarone and indene resins, ester gum,rosin, natural resins, such as copal, congo, kauri, etc. The urea resinsas well as the melamine resins are known to be extremely sensitive toacids, even to acidic pigments. Since they are immediately set" by acidsthe paint chemist would be immediately aware that they should not beused in our compositions.

Ester and ethers of cellulose such as nitrocellulose, cellulose acetate,ethyl cellulose, cellulose aceto-butyrate, etc. are also useful in ourimproved compositions.

Among the pigments are fillers we have found useful are fibrous talc orasbestine, silica, barytes, blanc flxe, titanium dioxide, titanatedgypsum and titanated barytes, carbon black, lampblaclr, red iron oxide,black iron oxide, chrome green oxide, smalt, etc. whiting or othercarbonates are inapplicable because of their well known reactivit withacids. Red lead may be used if the emulsions are freshly made Justbefore use. On

long standing red lead reacts deleteriously with acidity of 1.0 normal.

the acid in our compositions.

Ordinary driers and plasticizers may be present in our composition, and,in general, perform their usual functions.

Our invention has been found particularly useful on metals such as iron,steel, zinc and alloys thereof, although it has also been found usefulon cadmium, lead, copper and aluminum. In addition, our compositionshave yielded excellent results on concrete or cement surfaces and whenpainting such surfaces the preferable acids are, of course, those whichare capable of forming with the lime of the cement substantiallywaterinsoluble, inert and stable salts.

We claim:

1. A siccative paint including organic filmforming material emulsifiedas a dispersed phase in a continuous aqueous phase including phosphoricacid, together with a cation-active emulsifying agent; an organic liquidblending agent from the class consisting of aliphatic alcohols of notmore than eight carbon atoms and glycol ethers; a solvent in thedispersed phase which evaporates more slowly than water; and a pigmentsubstantially unaflectcd by the phosphoric acid; the concentration offree acidity in the aqueous phase being suflicient to impart to thatphase a pH of 4.5 but not more than enough to yield a free acidity of1.0 normal.

2. A siccative paint for use on metals including organic film-formingmaterial emulsified as a dispersed phase in a continuous aqueous phaseincluding phosphoric acid and a buffer salt from the class consisting ofthe phosphates of iron, zinc, manganese, calcium, cadmium and magneslum,together with a cation-active emulsifying agent; an organic liquidblending agent from the class consisting of aliphatic alcohols of notmore than eight carbon atoms and glycol ether-s; a solvent in thedispersed phase which evaporates more slowly than water; and a pigmentsubstantially unaffected by the phosphoric acid; the concentration offree acidity in the aqueous phasebeingsuilicienttoimparttothatphaseapfloi' 4.5 but not more than enoughto yield a free GER'l'IFICliTE or comc'rzos.

Patent No. 2,385,800.

October 2, 19 6.

ALFRED DUUTY, ET AL- It is herebycertified that error appears in theprinted specification of the above numbered patent requiring correctionas follows: Page 2,

column, line 75, for use" read --us--; and

page 5, first column, line 35, for "are" read "and";

read --aci.d-;

first second column, line 9, for"aci.ds"

and

second column, line a, beginning with "and when" strike out all to andincluding the word "salts" in line 12; and that the said Letters Patentshould be read with this correction therein that the some may conform tothe record of the case in the Patent Office.

(Seal) i. o. 191L6- Leslie Frazer First Assistant domissioner ofPatents.

